64-MDCT for diagnosis of aortic regurgitation in patients referred to CT coronary angiography.

OBJECTIVE: In clinical practice, 64-MDCT coronary angiography is increasingly being used for exclusion of coronary artery disease. Therefore, the purpose of this study was to evaluate whether aortic valve regurgitation can be diagnosed with 64-MDCT in comparison with transthoracic echocardiography.

MATERIALS AND METHODS: Eighty-one consecutive patients were examined with ECG-gated CT coronary angiography using image reconstruction during end-diastole. The diagnostic criterion for aortic valve regurgitation by CT was an incomplete coadaptation of aortic valve leaflets, the central aortic regurgitation area (ARA), which was quantified. All patients underwent transthoracic echocardiography using semiquantitative grading of aortic valve regurgitation (i.e., mild, moderate, or severe).

RESULTS: Of the 81 patients, 45 had aortic valve regurgitation by transthoracic echocardiography. The diagnostic accuracy of CT in detecting aortic valve regurgitation was as follows: sensitivity of 73% (33/45), specificity of 97% (35/36), positive predictive value (PPV) of 97% (33/34), and negative predictive value (NPV) of 74% (35/47). All 12 false-negative findings by CT were graded as mild regurgitation by transthoracic echocardiography and were caused by severe valve calcification (mean, 3,053.1 +/- 1,700 Agatston units; range, 937.7-5,632.5 Agatston units), bicuspid valves, or both. The sensitivity, specificity, PPV, and NPV of CT for the detection of moderate and severe aortic valve regurgitation were 95%, 100%, 100%, and 98%, respectively. Quantification of the ARA by CT (mean, 0.25 cm(2) +/- 0.34 cm(2) [SD]) was significantly correlated with the severity of aortic valve regurgitation by trans thoracic echocardiography (p < 0.001).

CONCLUSION: Although 64-MDCT accurately detects moderate and severe aortic regurgitation in patients referred to coronary CT angiography, mild aortic regurgitation can be missed on 64-MDCT in the presence of severe valve calcification or bicuspid valves.